Synthetic filling materials have become well accepted as inexpensive filling materials in bedding, furniture, apparel articles and similar applications. These materials, generally made of polyester, are appreciated for their bulk and hand.
Fiberfill has traditionally been used in a form of carded webs which are cross-lapped to build up their thickness into batts which are then used to fill the pillows, quilts or other articles. A large variety of fibers with different cross sections, bulk, deniers and blends of the different fibers have been used to produce the desired resilience and softness, and have usually been coated with a silicone slickener coating to reduce the fiber/fiber friction and to give the batt better softness and improved recovery from compression, as disclosed, for example, by Hoffmann in U.S. Pat. No. 3,271,189 and in Mead U.S. Pat. No. 3,454,422; instead of a silicone, some non-Si slickeners have been used, as described in my U.S. Pat. No. 4,818,599 and art referred to therein and in other prior art.
A batt structure does not allow the filling to move around and shape itself to the user's contours and to be refluffed back to the original shape after use, unlike natural fillings. Down and down/feather blends are characterized by their ability to shape to the user's contours and to be easily refluffed by shaking and patting back to the original shape. So there have been several suggestions and attempts to replicate down-like properties using synthetic fibers.
Miller U.S. Pat. No. 3,892,909, entitled "Synthetic Down", suggested using two types of bodies made from synthetic fibers as a filler, e.g., for pillows. Miller suggested larger bodies in the form of a figure of revolution, such as spheres or cylinders, to make up most of the mass of the stuffing of a pillow, and feathery bodies to fill the voids between the larger bodies. Miller's feathery bodies were unilateral or bilateral bundles of staple fibers or filaments joined at the center (bilateral) or at one end (unilateral). Miller's bundles were sprayed with a compatible binder that was applied in such a way as to bind the fibers at points of intersection, and desirably to obtain uniform distribution of the binder throughout the entire extent of the body. Other methods suggested for preserving shape were fusion by conventionally applied heat, impulse heating, laser or ultrasonic energy and chemicals.
A later suggestion was by Tani et al. in U.S. Pat. No. 4,418,103. Tani suggested a process that started from a tow of crimped continuous filaments (e.g., of polyester), involving (1) opening the tow, (2) compressing the ends of the filaments (in an end of the tow) together to a specified very high fiber density in a narrow slit or groove, (3) cutting the tow (filaments) to expose a cut end surface, (4) fusing the ends of the filaments together while they were still maintained in their high fiber density compressed condition in the narrow slit or groove, (5) advancing the tow to advance the now fused ends of the filaments to a desired distance from the narrow slit or groove, and (6) cutting the tow filaments so they were released from the narrow slit or groove, and then repeating steps 4-6 while continuing to hold the end of the tow in compressed condition except insofar as he advanced the tow periodically in step (5). Tani said that, when his filaments were cut (step 6), they spread spherically or radially about the end that was fused. Tani illustrated his process in his FIG. 1. Tani said that the resulting spherical masses could be used as filling material. To obtain down-like filling material, Tani suggested dividing the spherical masses into smaller cotton-like material composed of about a dozen to 200 fibers, and illustrated this in his FIG. 2. Tani emphasized that the crimped fibers in his filling material were always bonded together at one end at high 20 density, while the other ends of the fibers stayed free. This was an inevitable result of Tani's process, because he fused the ends of his filaments, so that the cut fibers would be connected only at their ends, which is where they were fused (so his resulting filling material extended almost twice the (crimped) length that he cut). Tani indicated that he could use other bonding methods.
I believe that neither Miller's nor Tani's suggestions have ever been manufactured or sold commercially. In contrast, however, the problem of providing a fiberfill product with the ability to move around inside the ticking to shape to the user's contours and then be refluffed back to regain the original shape was essentially solved on a commercial scale in 1985-6 by the provision of fiberballs, as disclosed in my U.S. Pat. Nos. 4,618,531 and 4,783,364, and in U.S. Pat. No. 5,112,684, for example. These patents refer to various previous suggestions in the art for preparing substitutes for feather or down.
Fiberballs (or clusters, as they are referred to sometimes) have approached natural fillings such as down in reproducing their ability to move inside the ticking and refluff, and have been used successfully in pillows and furniture back cushions. Further improvements would, however, be desirable.
According to my present invention, I now provide a new structure that achieves three dimensional fiber distribution and has a narrow, small, bonding point analogous to what characterizes down. I regard it as important to have a fiber tuft with completely opened fibers, where there is no restriction to the complete development of the fibers' bulk other than a small bonding point, preferably only one such in each tuft. I regard a bonding point as necessary to avoid clumping and ensure refluffability by maintaining the identity of the individual tufts during use. Contrary to fiberballs, in which fibers have been rolled together and cluster identity is maintained by entanglement of the fibers, the fibers in the present invention are fully opened and develop their bulk fully. The structure of my invention can have the advantages of being soft, refluffable, washable in a laundry machine, and providing improved insulation. It combines the advantages of the refluffability of the fiberballs with the insulation of the fiber batts.
The tufts of my invention need not be only bonded at the ends of the fibers as Tani suggested, nor only joined at the center or at one end as Miller suggested, but may be at any location in the individual tuft. Indeed, a mixture, wherein the bonding locations vary along the lengths of the fibers, has been a result and characteristic of my new process and I have found that the fact that the bonding is not always at the same location for all the tufts of my invention has given excellent results and is an advantage.
The bonding itself can be achieved using different means, but I prefer bonding techniques which allow me to bond the fibers effectively using as small a section of the fibers as reasonably possible and damaging as little as possible of the bulk of the fiber sections adjacent to the bonding area, to maximize bulk. I have found that a convenient technique for achieving such bonding uses ultrasonic bonding.